The present invention provides certain new Mycoplanecin derivatives, referred to herein as Mycoplanecin B and Mycoplanecin C, which may be prepared by cultivation of actinomycetes, and compounds prepared by reducing and/or hydrolizing Mycoplanecin B and Mycoplanecin C. The invention also provides processes for preparing these compounds as well as pharmaceutical compositions containing them.
U.S. patent application Ser. No. 041,501 filed May 22, 1979, which issued as U.S. Pat. No. 4,336,249 discloses an antibiotic substance called Mycoplanecin, which may be prepared by cultivating a Mycoplanecin-producing microorganism of the genus Actinoplanes, especially Actinoplanes nov. sp. Strain No. 41042 (FERM 4504). For clarity, this original Mycoplanecin compound is hereafter referred to as "Mycoplanecin A". Subsequently, U.S. patent application Ser. No. 199,238, filed Oct. 21, 1980, disclosed some derivatives of this Mycoplanecin A prepared by reducing the N-(.alpha.-ketobutyryl)-N-methylvalyl group of Mycoplanecin A to an N-(.alpha.-hydroxybutyryl)-N-methylvalyl group or by hydrolizing either Mycoplanecin A or the product obtained by reducing Mycoplanecin A. Mycoplanecin A and its two derivatives have the formula: ##STR2## [wherein: R represents a hydrogen atom, an N-(.alpha.-ketobutyryl)-N-methylvalyl group or an N-(.alpha.-hydroxybutyryl)-N-methylvalyl group]. Mycoplanecin A is the compound in which R represents an N-(.alpha.-ketobutyryl)-N-methylvalyl group. Mycoplanecin A and its derivatives have been found to have antibacterial activity, especially against microorganisms of the genus Mycobacterium. We have now discovered that other compounds, structurally related to Mycoplanecin A, can also be produced by microorganisms of the genus Actinoplanes and that these compounds and derivatives thereof also have antibacterial activity.